In tool and machine shops, precision gauges are used to verify that a machined article has been manufactured within the desired tolerances. A height gauge is used to verify that the vertical dimension is what it ought to be. A precision gauge is mounted on a support stand and positioned upon a granite surface plate that has been polished to have a surface flatness within millionths of an inch. Gauge blocks which have been ground and lapped to a particular dimension are used to calibrate the height gauge and the measurement transferred to the machined article to verify that it is within tolerance.
A number of support stands are available for supporting a precision gauge for comparing an article to a known standard as part of this quality control check in a machining or assembly operation. These supports typically have a vertical post to which a support arm is attached by a bracket. The support arm mounts the precision gauge and can be moved up and down the post for rough positioning of the gauge relative to the gauge block. Typically, a fine adjustment is available to position the gauge finger on the top of the gauge block. A rotatable dial on the gauge permits the force with which the gauge finger engages the gauge block to be zeroed out so the gauge finger is set at the precise height of the gauge block. The height gauge support stand can then be slid over the gauge plate surface to position the gauge finger above a machined article to determine if it is within the desired tolerance range. If several articles or dimensions on the same article are to be measured, typically a plurality of height gauge supports will be utilized so that once set, the gauge can be left in its adjusted position and simply repeatedly used to measure sequential articles. Most such gauge supports have a machined surface that may be brought into contact with a lateral face of the article to check its squareness.
One such support is described in U.S. Pat. No. 4,284,257 issued to David Murkens. This support has a split plate design with the upper and lower halves interconnected along one end face by a spring plate bolted to each half. Precision adjustment is effected by rotating a knob about a vertical axis pushing against the lower plate in order to tilt the upper plate with a vertical support post and the gauge attached. Due to the large number of parts, this design is expensive to manufacture and assemble. Also, its operation requires two hands, one to steady the stand and one to rotate the adjustment knob. In addition, the torquing of the adjustment screw about the vertical axis can cause the entire support to turn the article engaging tip of the height measuring gauge off the workpiece being measured. This can slow down the measuring process and aggravate the workman.
A second known device is available from Starn Tool and Manufacturing Company. This gauge support has a machined longitudinal beam that slides inside an outer gauge support block. The longitudinal beam has three different dimensions and an aperture which must be machined from a solid block of material and the support block must have a precision internal opening machined, as well. An adjustment screw extends vertically through a portion of the support block and engages an end of the longitudinal beam in order to permit tilting adjustment of the beam and the post it supports. This height measuring gauge suffers from the same problems associated with the Murkens device: it is expensive to manufacture, rotation of the adjustment knob requires two hands and torques the entire support about a vertical axis, which can cause movement of the article engaging finger.
The present invention overcomes the difficulties of the prior art by providing an adjustment screw that rotates about a horizontal axis on a front portion of the base, where it is out of the way. The base of the support stand is tapered to fit easily in the hand of the worker with grooves on each side for the fingers and thumb. The base can be gripped between the thumb and middle fingers while the index finger is used to rotate the adjustment screw permitting one-handed operation. In this manner, the force is generally down into the surface plate increasing resistance to movement of the base rather than creating a shear force between the surface plate and base tending to cause movement. Also, the adjustment knob can be rotated by pulling or pushing the periphery of the knob toward the thumb or middle finger of the hand gripping the base such that the component of the force that is not reacted into the support is offset by an opposing force from the thumb or middle finger.
The base is heavier than many others which are available, making it more stable. Further, the base has three point contact with the surface plate which also improves stability since three point contact will not rock, although four point contact might. In addition, three point contact reduces friction with the plate making it easier to move over the surface plate when being positioned relative to the workpiece.
The thread pitch on the adjustment knob screw is finer than most adjustment screws making the positioning of the gauge finger easier to accomplish. The fact that the adjustment screw is larger in diameter makes it easier to turn since the point at which the force is applied is further from the rotational axis increasing the length of the moment arm which reduces the magnitude of the tangential force required to produce rotation. Squareness checking rails are provided on both the front and rear faces of the base to enhance the utility of the device.
Various other features, advantages and characteristics of the present invention will become apparent to one of ordinary skill in the art after a reading of the following specification.